How do I use Pandas to find the unique values in a column and sort them?

How do I use Pandas to find the unique values in a column and sort them?

Pandas is a popular Python library used for data analysis and manipulation. One of its useful features is the ability to find unique values in a column and sort them. To do this, first import the Pandas library and read in your data as a Pandas DataFrame. Then, use the unique() function on the desired column to retrieve all the unique values. Finally, use the sort_values() function to sort the values in ascending or descending order. This approach allows for efficient identification of distinct values in a dataset and enables further analysis and processing.

Pandas: Find Unique Values in Column and Sort Them


You can use the following basic syntax to find the unique values in a column of a pandas DataFrame and then sort them:

df['my_column'].drop_duplicates().sort_values()

This will return a pandas Series that contains each unique value in a column sorted in ascending order.

To instead sort the unique values in descending order, use ascending=False:

df['my_column'].drop_duplicates().sort_values(ascending=False)

The following example shows how to use this syntax in practice.

Example: Find Unique Values in Pandas Column and Sort Them

Suppose we have the following pandas DataFrame:

import pandas as pd

#create DataFrame
df = pd.DataFrame({'team': ['A', 'A', 'A', 'A', 'A', 'B', 'B', 'B', 'B', 'B'],
                   'points': [5, 5, 9, 12, 12, 5, 10, 13, 13, 19]})

#view DataFrame
print(df)

  team  points
0    A       5
1    A       5
2    A       9
3    A      12
4    A      12
5    B       5
6    B      10
7    B      13
8    B      13
9    B      19

We can use the following syntax to get the unique values from the points column and then sort them in ascending order:

#get unique values in points column and sort them
df['points'].drop_duplicates().sort_values()

0     5
2     9
6    10
3    12
7    13
9    19
Name: points, dtype: int64

The output displays each of the unique values in the points column sorted in ascending order:

  • 5
  • 9
  • 10
  • 12
  • 13
  • 19

We can also get the unique values in the points column sorted in descending order by specifying ascending=False within the sort_values() function:

#get unique values in points column and sort them in descending order
df['points'].drop_duplicates().sort_values(ascending=False)

9    19
7    13
3    12
6    10
2     9
0     5
Name: points, dtype: int64

The output displays each of the unique values in the points column sorted in descending order:

  • 19
  • 13
  • 12
  • 10
  • 9
  • 5

The following tutorials explain how to perform other common functions in pandas:

Cite this article

stats writer (2024). How do I use Pandas to find the unique values in a column and sort them?. PSYCHOLOGICAL SCALES. Retrieved from https://scales.arabpsychology.com/stats/how-do-i-use-pandas-to-find-the-unique-values-in-a-column-and-sort-them/

stats writer. "How do I use Pandas to find the unique values in a column and sort them?." PSYCHOLOGICAL SCALES, 24 Jun. 2024, https://scales.arabpsychology.com/stats/how-do-i-use-pandas-to-find-the-unique-values-in-a-column-and-sort-them/.

stats writer. "How do I use Pandas to find the unique values in a column and sort them?." PSYCHOLOGICAL SCALES, 2024. https://scales.arabpsychology.com/stats/how-do-i-use-pandas-to-find-the-unique-values-in-a-column-and-sort-them/.

stats writer (2024) 'How do I use Pandas to find the unique values in a column and sort them?', PSYCHOLOGICAL SCALES. Available at: https://scales.arabpsychology.com/stats/how-do-i-use-pandas-to-find-the-unique-values-in-a-column-and-sort-them/.

[1] stats writer, "How do I use Pandas to find the unique values in a column and sort them?," PSYCHOLOGICAL SCALES, vol. X, no. Y, ص Z-Z, June, 2024.

stats writer. How do I use Pandas to find the unique values in a column and sort them?. PSYCHOLOGICAL SCALES. 2024;vol(issue):pages.

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